To maximize the benefits of highly active antiretroviral therapy (ART), patients must remain in treatment and adhere strictly to dosing regimens. However, remaining in care and continuing treatment while maintaining high adherence has proven difficult for many, including pregnant and postpartum women (PPPW). There is thus an urgent need to identify interventions that can improve retention and adherence behavior among PPPW, especially in developing countries, home to the majority of HIV-positive individuals. At the same time, technology offers the potential to tap into new intervention approaches. Zambia has one of sub-Saharan Africa's worst HIV epidemics and, in response, ART access has been scaled up rapidly, including a new policy-'Option B+'-which provides free ART to all HIV-positive pregnant women. However, little is known about ways to promote retention in care and ART adherence in Zambia. The broad goal of the proposed study is to help fill these knowledge gaps by increasing knowledge of feasible and effective interventions to improve retention and adherence in PPPW. The specific aims are to: 1) test the acceptability and feasibility of Wisepill use by pregnant and postpartum women PPPW; 2) evaluate effectiveness of 2-step feedback on retention in care and ART adherence among PPPW; and 3) explore PPPW and provider perspectives on barriers and facilitators to retention in care and ART adherence. The study will achieve these aims over 2.5 years by implementing a randomized controlled trial to assess 2-step feedback, an intervention that utilizes wireless technology via an electronic pill container ('Wisepill'), and investigating factors (positive and negative) that influence retention in care an adherence using quantitative and qualitative research methods. We will enroll 130 pregnant women who are initiating ART in Livingstone, Southern Province, Zambia. The approximately 6- month intervention, timed to end at 3 months postpartum for each woman, will provide: 1) personalized cell phone text message reminders to PPPW who fail to take a dose on time and 2) monthly counseling with a lay counselor informed by patients' adherence data, focused on overcoming retention and adherence barriers and supporting positive retention and adherence behaviors. The comparison arm will provide adherence data via Wisepill and receive usual care, including counseling with lay counselors per standard of care (without adherence data). The study will follow all patients for an additional 3 months until 6 months postpartum to determine sustainability of the impact of the intervention. In addition to adherence and clinical data, quantitative and qualitative data will be collected using survey instruments and in-depth interviews. Analysis of these data will enable achievement of the specific aims, contribute to the scientific evidence base on effective approaches to improving retention and adherence behavior in PPPW, and potentially other patients, and have a high potential for policy and program impact due to strong support from Zambian officials. The proposed Boston- Zambia team of experienced researchers has exceptional capacity to conduct the study.